1. Field of Invention
The present invention generally relates to high intensity discharge (HID) lamps and more specifically to a drop-in HID lamp assembly and retrofit method of deploying same, e.g., in aircraft lighting applications.
2. Brief Description of the Related Art
In the field of aircraft lighting, a wide variety of lighting elements and fixtures have been employed for interior (cabin) as well as exterior lighting applications.
Among the lights employed in exterior aircraft lighting systems, landing lights and taxi lights are particularly critical for safety and operability of the aircraft.
Conventional commercial passenger aircraft such as the Boeing 737, 747 and 777 (The Boeing Company, Chicago, Ill.) and many Airbus jetliners (Airbus S.A.S., Toulouse, France) use a common 28 volt 600 watt incandescent halogen Parabolic Aluminized Reflector (PAR) 64 lamp (Part No. Q4559X or Part No. Q4559XX) for landing and taxi lights. In incandescent PAR lamps, the bulb and reflector are encased in a glass housing, with the entire lamp ranging from M16 to PAR 64, and beam patterns ranging from Aircraft Landing (ACL) at the narrow end to very wide. Lamps are measured in increments corresponding to ⅛ inch (e.g., A PAR 36 is 36 times one eighth inch or 4½″ in diameter). Typical output of incandescent halogen PAR lamps for such aircraft lighting applications is in the vicinity of 700,000 candelas (cd) with a 10×12 (spot) angle.
A significant deficiency of such PAR 64 lamps is their short service life, which in typical aircraft exterior lighting applications is on the order of 10-20 hours. The failure mode of such lamps is almost invariably associated to cracked lenses or filament failure.
Change-out of failed PAR 64 lamps, as a result of their short operating life, represents a major maintenance issue, since such lighting is intended for continuous functioning during night or low visibility conditions.
There is therefore a need in the art for aircraft taxi and landing lights that provide long service life and are readily deployed and efficient in use, and that, ideally, could be retrofitted to existing PAR 64 lighting assemblies, thereby avoiding the necessity of out-of-service periods for rewiring and fitting of new lighting systems.
In addition to providing long service life and high efficiency, it would also be desirable for a retrofit assembly to have readily replaceable parts so as to minimize waste, time, and expense associated with periodic maintenance to sustain light-generating operation.